Scroll type fluid machine

ABSTRACT

A scroll type fluid machine having a rotation-preventing member extending between at least one of a fixed scroll and a housing which form a non-orbiting part and a movable scroll and preventing rotation of the movable scroll, and also having a mechanism for making the rotation-preventing member movable, the mechanism being provided to the rotation-preventing member for permitting a movement of the rotation-preventing member itself which movement is required for the rotation-preventing member to permit an orbital movement of the movable scroll. The scroll type fluid machine, with the rotation-preventing mechanism for the movable scroll, can be easily assembled into a target assembly condition, and can be formed to be small-sized and light-weighted.

TECHNICAL FIELD OF THE INVENTION

The present invention relates to a structure of a scroll section of a scroll type fluid machine such as a scroll type compressor, and specifically relates to a rotation preventing mechanism of a movable scroll and a structure of a scroll section relating thereto.

BACKGROUND ART OF THE INVENTION

In a scroll type fluid machine, a fixed scroll and a movable scroll which orbits as prevented from its rotation relative to the fixed scroll are engaged with each other and form a fluid pocket in between. The fluid is compressed by moving the fluid pocket in a radial direction so as to reduce its volume in a compressor, or the fluid is expanded by moving the fluid pocket in a radial direction so as to extend its volume in an expansion machine. In such a scroll type fluid machine, the movable scroll has to be orbited as prevented from its rotation. To prevent the rotation, known are prior arts such as a coupling called a ball coupling or EM coupling, a pin-and-ring coupling and a pin-and-link coupling. However as for all these, the coupling in itself has had an intrinsic orbiting radius so that it cannot coincide completely with the orbiting radius and the movable scroll trajectory, which are defined by the scroll wall.

On the other hand, a prior art using a coupling called Oldham's coupling for preventing the rotation of the movable scroll is known. The Oldham's coupling does not have its intrinsic orbiting radius but it vibrates by its reciprocation and because the span between a bearing provided in the movable scroll and another bearing provided in a housing may increase by the thickness of the Oldham's coupling, the moment load to the bearing may increase and therefore the speedup may be difficult.

In addition Patent document 1 discloses a structure where the movable scroll wobbles like a swing by the rotation of a crankshaft. But it is too difficult to keep balance, and therefore the speedup may be difficult.

Furthermore, Patent documents 2, 3, 4 and 5 disclose structures where the movable scroll is prevented from its rotation by a ditch provided on a bottom plate of the movable scroll and a pin provided in the housing.

PRIOR ART DOCUMENTS Patent documents

Patent document 1: JP-2751318-B

Patent document 2: JP-3874018-B

Patent document 3: JP-3976070-B

Patent document 4: JP-3976081-B

Patent document 5: JP-4013992-B

SUMMARY OF THE INVENTION

Problems to be solved by the Invention

However in the rotation preventing mechanism with its own intrinsic orbiting radius as described above, displacements to the orbiting radius of the movable scroll or to the trajectory of the movable scroll may bring about deterioration of the fluid machine performance and durability as well as noise and vibration.

In addition, the Oldham's coupling is unsuitable for the speedup as described above, and because it requires some space to be installed the miniaturization may be difficult.

Further, the rotation preventing mechanism disclosed in Patent document 1 is unsuitable for the speedup as described above and the miniaturization may be difficult.

Furthermore, the rotation preventing mechanisms, which are disclosed in Patent documents 2-5, do not consider about the degree of increase/decrease of the scroll wall-thickness from the center toward the outer circumference of the movable scroll. But because the scroll wall-thickness sometimes changes for miniaturization, etc., when the scroll wall-thickness changes excessively, a tip seal provided in the scroll forefront side may be difficult to be attached and may be difficult to ensure stable performance. In addition, because they do not consider about angle displacements of the scroll, the performance or the vibration and noise may be affected by dimensional variations.

Further, in the rotation preventing mechanisms disclosed in Patent documents 2-5, movable scrolls are permitted to perform an orbital movement accompanying the circumnutation movement up to 180 degree in the worst. Usually the scroll wall is formed as interposed between spiral curves within 90 degree phase difference, however the above prior arts with great circumnutation angle may deviate from the range and for example in such a case, the fixed scroll wall cannot be formed.

Accordingly, an object of the present invention is, as focusing on each problem in the above described various conventional rotation preventing mechanism, to provide a scroll type fluid machine having a rotation preventing mechanism of a movable scroll, which does not have its own intrinsic orbiting radius, which can be easily assembled into a target assembled condition with high accuracy, which can stably show high productivity, silence and performance, which can be easily miniaturized specifically in the axial direction and can be even reduced in weight because no rotation preventing section exists between a movable scroll and a housing, and which can easily provide a desirable profile of a fixed scroll wall to be able to seal adequately, with relatively small circumnutation angle of the movable scroll.

In addition, another object of the present invention is to ensure smoother movement of the rotation preventing mechanism by a lubrication for a certain part, which is regarded as preferable to be lubricated, of a rotation preventing mechanism of the movable scroll as effectively using the lubricating oil circulation route for a whole scroll type fluid machine. Also another object of the present invention is to contribute to upgrade a scroll type fluid machine as well as a whole system incorporating the scroll type fluid machine by desirable circulation of lubricating oil.

Means for solving the Problems

To achieve the above described objects, a scroll type fluid machine according to the present invention is a scroll type fluid machine comprising a fixed scroll, a movable scroll which engages the fixed scroll to form a fluid pocket being moved in a scroll radial direction, a crankshaft which engages the movable scroll to drive the movable scroll, and a housing which is provided with a bearing supporting the crankshaft, the movable scroll being orbited relative to the fixed scroll by a drive torque transmitted to through the crankshaft, characterized in that the fixed scroll and the housing form a non-orbiting part, and provided is a rotation-preventing member which extends between at least one of the fixed scroll and the housing forming the non-orbiting part and the movable scroll and which prevents the movable scroll from rotating, and also provided to the rotation-preventing member is a mechanism for making the rotation-preventing member movable, the mechanism permitting the rotation-preventing member's own movement required for permission of an orbital movement of the movable scroll by the rotation-preventing member.

In this scroll type fluid machine according to the present invention, it can be employed as the first embodiment that the rotation-preventing member comprises a member which is fixed to an outer circumferential section of the movable scroll and which extends from the outer circumferential section of the movable scroll radially outward, and the mechanism for making the rotation-preventing member movable is provided to at least one of the fixed scroll and the housing, and comprises a rotating-body space which has an axis line parallel with a main shaft section of the crankshaft and a rotating body which is rotatably fitted in the rotating-body space and which slidably supports the rotation-preventing member. For example, the rotation-preventing member such as a plate member is constructed integrally with a scroll wall of the movable wall. If the rotation-preventing member is prevented from its movement in a rotational direction of the movable scroll, the movable scroll is prevented from rotating. Because the movable scroll must move as orbiting as well, the rotation-preventing member must be also permitted to move in a wobbling direction and a sliding direction so as to permit its orbiting movement. It is possible to employ an embodiment, comprising the rotating-body space and the rotating body, where mechanism to enable the movement of the rotation-preventing member is provided. More concretely, it is possible that the rotating body comprises a pair of columnar shoes each having an arc surface and a flat bottom surface, and supports the rotation-preventing member slidably between flat bottom surfaces facing to each other.

In addition, in the scroll type fluid machine according to the present invention, it is preferable that a distance from a center axis of the rotating-body space to a center axis of the main shaft section of the crankshaft is set in a range of 1.5 - 15 times of an orbiting radius of the movable scroll so that the rotation-preventing member is controlled to move appropriately for performing surely the rotation prevention of the movable scroll by the above described rotating body and the rotating- body space.

In addition, for more concrete design, it is preferable that when the rotating-body space is referred to as a cylindrical space having a diameter of D1, a thickness in a maximum thickness section determined based on the flat bottom surface with one of the cylindrical shoes is referred to as T1, a thickness in a maximum thickness section determined based on the flat bottom surface with the other of the cylindrical shoes is referred to as T2, and a thickness of the rotation-preventing member is referred to as Ts, they are set to satisfy a relation represented by the following equation: D1>T1+T2+Ts. By such design, while the rotation-preventing member can be supported as slidably, the pair of columnar shoes can smoothly perform a desirable movement as a rotating body.

Further in the scroll type fluid machine according to the present invention, it is possible to effectively utilize the lubrication oil circulation structure in the scroll type fluid machine which was formerly proposed in Japanese patent application No. 2008-83834 filed by the applicant. In other words, it is possible that a back surface of the movable scroll slides on the housing and forms a space for containing a drive mechanism section of the crankshaft which is partitioned from a suction chamber, a lubricating oil route is provided for supplying lubricating oil from an oil sump formed below a discharge chamber into the drive mechanism section containing space (The former proposal is up to here.), and the lubricating oil route is formed through the rotating-body space. The lubricating oil is supplied and circulated from an oil sump below the discharge chamber into the drive mechanism section containing space of the crankshaft, so as to improve the lubricity of the drive mechanism section, the substantive volumetric efficiency of the fluid machine, and heat exchange efficiency of this system incorporated in the fluid machine by reducing the lubricating oil flow out of the fluid machine, and to reduce the power for the fluid machine and the system by reducing the pressure loss inside pipes. The lubricating oil route is formed through the rotating-body space, so that the rotating body and the rotation-preventing member part can be lubricated well to enable smoother operation.

Furthermore, the mechanism in the scroll type fluid machine according to the present invention can be easily applied specifically to form the lubricating oil route when the scroll type fluid machine is formed as a horizontal-type one in which the main shaft section of the crankshaft is extended in a horizontal direction at a time during operation. In addition, though the location of the rotation-preventing member or the rotating-body space is not limited, an orbiting position of the movable scroll and the lubricating oil can be easily designed if the rotating-body space is located above or below the fixed scroll.

In the scroll type fluid machine according to the present invention, it can be employed as the second embodiment that the rotation-preventing member comprises a member which is engaged free to rotate with an outer circumferential section of the movable scroll and which extends from the outer circumferential section of the movable scroll radially outward, and the mechanism for making the rotation-preventing member movable is provided to at least one of the fixed scroll and the housing, and comprises a hole for reciprocating sliding which extends in a direction orthogonal to a main shaft section of the crankshaft and which slidably supports the rotation-preventing member. In that construction, the rotation-preventing member engaged free to rotate at the movable scroll side is slidably supported by the hole for reciprocating sliding. This construction can prevent the movable scroll from rotating as ensuring a predetermined orbiting movement of the movable scroll as well.

In the second embodiment, in order to perform the rotation prevention properly, it is preferable that wherein an engagement section of the rotation-preventing member engaged free to rotate with the outer circumferential section of the movable scroll is located at a place from which a distance to a center axis of the main shaft section of the crankshaft in the movable scroll is set at 1.5 times or more of an orbiting radius of the movable scroll.

Further, in the second embodiment, it is possible to effectively utilize the lubrication oil circulation structure in the scroll type fluid machine which was formerly proposed in Japanese patent application No. 2008-83834 filed by the applicant. In other words, it is possible that a back surface of the movable scroll slides on the housing and forms a space for containing a drive mechanism section of the crankshaft which is partitioned from a suction chamber, and a lubricating oil route is provided for supplying lubricating oil from an oil sump formed below a discharge chamber into the drive mechanism section containing space, and the lubricating oil route is formed through the hole for reciprocating sliding.

Furthermore, in the second embodiment, the mechanism according to the present invention can be easily applied specifically to form the lubricating oil route when the scroll type fluid machine is formed as a horizontal-type one in which the main shaft section of the crankshaft is extended in a horizontal direction at a time during operation.

In addition, in the scroll type fluid machine according to the present invention including the first and second embodiments described above, it is preferable that a center of a bearing of a back surface of the movable scroll is coincident with the origin of a spiral curve forming a scroll wall, and a center of a main shaft section of the crankshaft supported rotatably by a bearing of the housing is coincident with the origin of a spiral curve forming a scroll wall of the fixed scroll. Such a construction can prevent a scroll wall at the counterpart from becoming too thin.

Further, in the scroll type fluid machine according to the present invention, it is preferable that a bush integrated with a counterweight is interposed between a crankpin of the crankshaft and a bearing of a back surface of the movable scroll, so that torque is transmitted from the crankpin to the movable scroll at the same time that a centrifugal force in the movable scroll is cancelled to be decreased. That can construct a driven crank mechanism ready for various positions and shapes of the scroll wall prepared so as to enhance productivity and the efficiency of the fluid machine by improving seal performance of the scroll wall.

Furthermore in the scroll type fluid machine according to the present invention, it is preferable that wall thickness of a scroll wall of either or both of the movable scroll and the fixed scroll becomes smaller in an outward direction. In other words, the thickness of the scroll wall is reduced in one way without the increase and decrease being repeated in the wall thickness of the scroll wall. That can make it reduced in size and weight.

The scroll type fluid machine according to the present invention can be formed as a scroll type compressor or a scroll type expansion machine which are required to be reduced in size and weight and to operate smoothly. In addition, the scroll type fluid machine is suitable as an automotive scroll type fluid machine which is mounted on a vehicle.

Effect according to the Invention

A scroll type fluid machine can realize a rotation preventing mechanism of a movable scroll which can be easily installed by high accuracy into a desirable installation condition without its intrinsic orbiting radius, by providing a rotation-preventing member of the movable scroll, the rotation-preventing member extending between the movable scroll side and a fixed member side, and also providing a mechanism for making the rotation-preventing member movable, the mechanism permitting the rotation-preventing member's own movement required for permission of an orbital movement of the movable scroll by the rotation-preventing member, so that productivity, silence and performance can be stably kept high as a whole fluid machine including the rotation preventing mechanism. In addition, because a rotation preventing section does not exist between the movable scroll and the housing in an axial direction, a miniaturization in an axial direction is specifically easy, so that the weight saving can be achieved. Further, because the circumnutation angle of the movable scroll can be kept small a desirable profile of the fixed scroll wall which can be sealed can be obtained easily.

Furthermore, the lubricating oil circulation structure in the scroll type fluid machine which has been proposed in Japanese patent application No. 2008-83834 filed by the applicant can be effectively utilized in the above described rotation preventing mechanism, smoother operation of the rotation preventing mechanism can be ensured. Also, the lubricating oil can be circulated desirably in the drive mechanism section side of the crankshaft, so as to contribute to improve a whole scroll type fluid machine and a whole system incorporating the scroll type fluid machine.

BRIEF EXPLANATION OF THE DRAWINGS

[FIG. 1] FIG. 1 is a longitudinal sectional view of scroll type fluid machine according to an embodiment of the present invention.

[FIG. 2] FIG. 2 is a cross sectional view of a scroll mechanism section of the fluid machine in FIG. 1.

[FIG. 3] FIG. 3 shows an elevational view (A) and a longitudinal sectional view (B), of the fluid machine in FIG. 1.

[FIG. 4] FIG. 4 shows various embodiments (A)-(C) which can be employable as a rotating body of the fluid machine in FIG. 1.

[FIG. 5] FIG. 5 shows an elevational view (A) and a longitudinal sectional view (B), of another embodiment of the fluid machine in FIG. 1.

[FIG. 6] FIG. 6 shows cross sectional views of the scroll mechanism section, where the orbiting operation and the rotation preventing operation of the movable scroll of the fluid machine in FIG. 1 are shown in order of (A)-(F).

[FIG. 7] FIG. 7 is a schematic framework of a scroll type fluid machine according to an embodiment other than in FIG. 1.

EMBODIMENTS FOR CARRYING OUT THE INVENTION

Hereinafter, desirable embodiments of the present invention will be explained referring to figures.

FIG. 1 and FIG. 2 show an embodiment of the aforementioned first embodiment of the present invention. In those figures, symbol 1 shows a whole scroll type fluid machine.

Scroll type fluid machine 1 has fixed scroll 2, movable scroll 3 engaging with fixed scroll 2 to form fluid pocket 4 which is moved in a scroll diameter direction, crankshaft 5 engaging with movable scroll 3 to drive movable scroll 3, and housing 7 provided with bearing 6 supporting crankshaft 5. Crankshaft 5 has crank pin 8 in an eccentric region, and the drive torque transmitted via crank pin 8, eccentric bush 9 fitting with it rotatably and bearing 10 makes movable scroll 3 orbit relative to fixed scroll 2 around main shaft section 5 a of crankshaft 5. Scroll type fluid machine 1 can function as a compressor by moving fluid pocket 4 toward the center as reducing its volume, and conversely, can function as a expansion machine by moving it outward in a diameter direction as extending its volume. In this embodiment, its function as a scroll type compressor will be explained particularly.

Fluid, such as refrigerant, sucked into suction chamber 11 is compressed by a scroll mechanism comprising fixed scroll 2 and movable scroll 3, and then discharged through discharge pore 12 provided in the center of fixed scroll 2 into discharge chamber 13, through which compressed fluid is delivered to an exterior circuit through discharge port 14. Below discharge chamber 13 oil sump 15 is formed in order to separate and trap lubricating oil contained in the fluid, such as refrigerant. Crankshaft 5 is driven to rotate by pulley 16 into which drive force is input from an external drive source, electromagnetic clutch 17 and armature 18, for example.

Fixed scroll 2 and housing 7 constitute a non-orbiting member. Rotation-preventing member 21 to prevent movable scroll 3 from rotating is provided, which extends between movable scroll 3 and either or both fixed scroll 2 and housing 7 (which constitutes fixed scroll 2 and which is fixed scroll member 20 interposed between housing 7 and cylinder head 19, in this embodiment). In this embodiment rotation preventing member 21 is formed integrally with movable scroll 3, extending like a plate outward in a diameter direction from outer circumferential section of the scroll wall of movable scroll 3 as shown in FIG. 3.

In addition to rotation-preventing member 21, mechanism for making rotation preventing-member movable 22 which permits rotation-preventing member 21 movement required for permission of orbital movement of movable scroll 3 by rotation-preventing member 21 is provided. In this embodiment, mechanism for making rotation-preventing member movable 22 is provided to either or both fixed scroll 2 and housing 7 (provided to fixed scroll member 20, in this embodiment), and comprises rotation-body space 23 having an axis line parallel to main shaft section 5 a of the crankshaft and rotating body 24 which is rotatably fitted in rotating-body space 23 and which slidably supports rotation-preventing member 21. Rotating body 24 is formed by a pair of columnar shoes 24 a, 24 b each having an arc surface and a flat bottom surface and supporting rotation-preventing member 21 slidably between flat bottom surfaces facing to each other.

As shown in FIG. 4, rotating body 24 can be formed into a shape of a pair of semicylinder bodies 24 a and 24 b, as well as rotating body 25 consisting of semicylinder bodies 25 a and 25 b, or rotating body 26 consisting of tapered semicylinder bodies 26 a and 26 b. In addition as for the shape and installation position of rotation-preventing member 21, as shown in FIG. 5 rotation-preventing member 32 can be formed integrally with movable scroll 31 in a back side shoulder section of movable scroll 31. Further in FIG. 5, symbol 33 shows the center of gravity of the scroll wall of movable scroll 31.

Referring to FIG. 1 again, in this embodiment the back surface of movable scroll 3 slides with housing 7 and drive mechanism section containing space 41 of crankshaft 5 is formed by partitioned from suction chamber 11. Lubricating oil route 42 capable of supplying lubricating oil into drive mechanism section containing space 41 is formed from oil sump 15 formed below discharge chamber 13, and drawing 43 is formed en route. Lubricating oil route 42 is formed through aforementioned rotating body space 23.

Further, lubricating oil route 42 can be easily formed especially in a horizontal scroll type fluid machine in which main shaft section 5 a of the crankshaft is extended in a horizontal direction at a time during operation. Furthermore, when rotation-preventing member 21 and rotating-body space 23 are located above or below fixed scroll 2, orbiting position of the movable scroll and lubricating oil route can be easily designed, therefore they are located above fixed scroll in this embodiment.

As to embodiments shown in FIG. 1 and FIG. 2, orbiting movement and rotation preventing operation of movable scroll 3 will be explained as referring to FIG. 6.

In FIG. 6, (A) shows a case where the phase (orbiting position) of the center of movable scroll 3 relative to the center of fixed scroll 2 is 0-degree, while (B), (C), (D), (E) and (F) show 60-, 120-, 180-, 240- and 300-degree phase cases respectively. Accompanying with a phase variation, movable scroll 3 wobbles right and left by a small angle in the figure together with rotation-preventing member 21, which thereby slides up and down in the figure between a pair of columnar shoes 24 a and 24 b of rotating body 24. At this time rotating body 24 is rotated as remained in rotating- body space 23. By these movement, rotation-preventing member 21 can permit movable scroll 3 to perform an orbital movement with little resistance. In addition, because rotation-preventing member 21 is always restricted at the position above movable scroll 3 (above fixed scroll 2), movable scroll 3 formed integrally with rotation-preventing member 21 is surely prevented from its rotation.

Thus, the aforementioned rotation preventing mechanism does not have its own intrinsic orbiting radius and is not required to be incorporated by high accuracy with another member or another mechanism substantively, so that it can be easily assembled by high accuracy into a desired assembled form. Further, high silence and durability can be expected because quantity of rotation and sliding are not required to be great. Therefore, high productivity, silence and performance are provided as a whole fluid machine including rotation preventing mechanism of movable scroll 3.

In addition, because the rotation preventing mechanism has neither member nor mechanism between movable scroll 3 and housing 7 in an axial direction, miniaturization in an axial direction is easily realized and weight saving can be achieved thereby.

Further, because the circumnutation angle, which means the waggling angle of rotation-preventing member 21, can be kept extremely small, a desirable profile of the wall at fixed scroll 2 side, in other words a desired profile of the fixed scroll wall which can be adequately sealed by a tip seal, etc., can be obtained easily.

Furthermore, because lubricating oil route 42 is formed through rotating-body space 23, lubricating oil which is returned from oil sump 15 formed below discharge chamber 13 into drive mechanism section containing space 41 is effectively utilized even in rotating-body space 23, so that smoother operation, such as rotation and sliding movement, of the aforementioned rotation preventing mechanism can be ensured. At the same time, lubricating oil can be desirably circulated at the drive mechanism section side of crankshaft 5 by lubricating oil route 42, so as to contribute to improve performance (such as improvement of heat exchange efficiency at the system side by reducing the oil circulation ratio in the system, and reduction of power consumption by reducing the pressure loss in pipes) of both a whole scroll type fluid machine 1 and a whole system including scroll type fluid machine 1.

In the present invention, as shown in FIG. 7 for the second embodiment described above, it is possible that rotation-preventing member 51 is formed as a member which is engaged free to rotate with an outer circumferential section of movable scroll 52 and which extends from the outer circumferential section of movable scroll 52 radially outward, and the rotation preventing mechanism for making the rotation-preventing member movable in the present invention is provided to either or both of the fixed scroll and the housing (in other words, is provided at fixed member 53 side), and is formed by hole 54 for reciprocating sliding which extends in a direction orthogonal to main shaft section 5 a of the crankshaft and which slidably supports rotation-preventing member 51. Even in this structure, movable scroll 52 is ensured to rotate in a predetermined way, so as to prevent movable scroll 52 from rotating.

Industrial Applications of the Invention

A scroll type fluid machine according to the present invention is applicable to a scroll type compressor and expansion machine, which are required to be reduced in size and weight and to perform smooth movement, and is specifically suitable for an automotive scroll type fluid machine which is required to be silent and durable.

Explanation of symbols

-   1: scroll type fluid machine -   2: fixed scroll -   3: movable scroll -   4: fluid pocket -   5: crankshaft -   5 a: main shaft section of crankshaft -   6: bearing -   7: housing -   8: crank pin -   9: eccentric bush -   10: bearing -   11: suction chamber -   12: discharge pore -   13: discharge chamber -   14: discharge port -   15: oil sump -   16: pulley -   17: electromagnetic clutch -   18: armature -   19: cylinder head -   20: fixed scroll member -   21: rotation-preventing member -   22: mechanism for making rotation-preventing member movable -   23: rotating-body space -   24: rotating body -   24 a, 24 b: columnar shoe -   25: rotating body -   25 a, 25 b: shoe -   26: rotating body -   26 a, 26 b: shoe -   31: movable scroll -   32: rotation-preventing member -   33: center of gravity of scroll wall of movable scroll -   41: drive mechanism section containing space -   42: lubricating oil route -   43: drawing -   51: rotation-preventing member -   52: movable scroll -   53: fixed member -   54: reciprocating sliding hole 

1. A scroll type fluid machine comprising a fixed scroll, a movable scroll which engages said fixed scroll to form a fluid pocket being moved in a scroll radial direction, a crankshaft which engages said movable scroll to drive said movable scroll, and a housing which is provided with a bearing supporting said crankshaft, said movable scroll being orbited relative to said fixed scroll by a drive torque transmitted to through said crankshaft, characterized in that said fixed scroll and said housing form a non-orbiting part, and provided is a rotation-preventing member which extends between at least one of said fixed scroll and said housing forming said non-orbiting part and said movable scroll and which prevents said movable scroll from rotating, and also provided to said rotation-preventing member is a mechanism for making said rotation-preventing member movable, said mechanism permitting said rotation-preventing member's own movement required for permission of an orbital movement of said movable scroll by said rotation-preventing member.
 2. The scroll type fluid machine according to claim 1, wherein said rotation-preventing member comprises a member which is fixed to an outer circumferential section of said movable scroll and which extends from said outer circumferential section of said movable scroll radially outward, and said mechanism for making said rotation-preventing member movable is provided to at least one of said fixed scroll and said housing, and comprises a rotating-body space which has an axis line parallel with a main shaft section of said crankshaft and a rotating body which is rotatably fitted in said rotating-body space and which slidably supports said rotation-preventing member.
 3. The scroll type fluid machine according to claim 2, wherein said rotation-preventing member is constructed integrally with a scroll wall of said movable wall.
 4. The scroll type fluid machine according to claim 2, wherein said rotating body comprises a pair of columnar shoes each having an arc surface and a flat bottom surface, and supports said rotation-preventing member slidably between flat bottom surfaces facing to each other.
 5. The scroll type fluid machine according to claim 2, wherein a distance from a center axis of said rotating-body space to a center axis of said main shaft section of said crankshaft is set in a range of 1.5-15 times of an orbiting radius of said movable scroll.
 6. The scroll type fluid machine according to claim 2, wherein, when said rotating-body space is referred to as a cylindrical space having a diameter of D1, a thickness in a maximum thickness section determined based on said flat bottom surface with one of said cylindrical shoes is referred to as T1, a thickness in a maximum thickness section determined based on said flat bottom surface with the other of said cylindrical shoes is referred to as T2, and a thickness of said rotation-preventing member is referred to as Ts, they are set to satisfy a relation represented by the following equation: D1>T1+T2+Ts.
 7. The scroll type fluid machine according to claim 2, wherein a back surface of said movable scroll slides on said housing and forms a space for containing a drive mechanism section of said crankshaft which is partitioned from a suction chamber, a lubricating oil route is provided for supplying lubricating oil from an oil sump formed below a discharge chamber into said drive mechanism section containing space, and said lubricating oil route is formed through said rotating-body space.
 8. The scroll type fluid machine according to claim 2, wherein said scroll type fluid machine is formed as a horizontal-type one in which said main shaft section of said crankshaft is extended in a horizontal direction at a time during operation.
 9. The scroll type fluid machine according to claim 8, wherein said rotating-body space is located above or below said fixed scroll.
 10. The scroll type fluid machine according to claim 1, wherein said rotation-preventing member comprises a member which is engaged free to rotate with an outer circumferential section of said movable scroll and which extends from said outer circumferential section of said movable scroll radially outward, and said mechanism for making said rotation-preventing member movable is provided to at least one of said fixed scroll and said housing, and comprises a hole for reciprocating sliding which extends in a direction orthogonal to a main shaft section of said crankshaft and which slidably supports said rotation-preventing member.
 11. The scroll type fluid machine according to claim 10, wherein an engagement section of said rotation-preventing member engaged free to rotate with said outer circumferential section of said movable scroll is located at a place from which a distance to a center axis of said main shaft section of said crankshaft in said movable scroll is set at 1.5 times or more of an orbiting radius of said movable scroll.
 12. The scroll type fluid machine according to claim 10, wherein a back surface of said movable scroll slides on said housing and forms a space for containing a drive mechanism section of said crankshaft which is partitioned from a suction chamber, and a lubricating oil route is provided for supplying lubricating oil from an oil sump formed below a discharge chamber into said drive mechanism section containing space, and said lubricating oil route is formed through said hole for reciprocating sliding.
 13. The scroll type fluid machine according to claim 10, wherein said scroll type fluid machine is formed as a horizontal-type one in which said main shaft section of said crankshaft is extended in a horizontal direction at a time during operation.
 14. The scroll type fluid machine according to claim 1, wherein a center of a bearing of a back surface of said movable scroll is coincident with the origin of a spiral curve forming a scroll wall, and a center of a main shaft section of said crankshaft supported rotatably by a bearing of said housing is coincident with the origin of a spiral curve forming a scroll wall of said fixed scroll.
 15. The scroll type fluid machine according to claim 1, wherein a bush integrated with a counterweight is interposed between a crankpin of said crankshaft and a bearing of a back surface of said movable scroll, so that torque is transmitted from said crankpin to said movable scroll at the same time that a centrifugal force in said movable scroll is cancelled to be decreased.
 16. The scroll type fluid machine according to claim 1, wherein wall thickness of a scroll wall of either or both of said movable scroll and said fixed scroll becomes smaller in an outward direction.
 17. The scroll type fluid machine according to claim 1, wherein said scroll type fluid machine is formed as a scroll type compressor or a scroll type expansion machine.
 18. The scroll type fluid machine according to claim 1, wherein said scroll type fluid machine is an automotive scroll type fluid machine which is mounted on a vehicle. 